It is difficult to relate variables in Vue to the first time user as they have several more dimensions than that of C. Scope can be complicated by the thread concept as well as relating context. Examples of these differences follow over the next few slides.

While Vue appears at first to be C based, Java and C++ developers may be more comfortable with some of the datatypes and (overloaded) operators Ð such as the ability to concatenate strings with the Ò+Ó operator.

The timestamp data type will seem familiar to those using the high resolution time functions that use the timeval structure such as gettimeofday(). The specific implementation details are not shared by IBM Ð but it is sufficient to say that mathematical comparisons on this data type essentially work like integers, but calculating differences on (subtracting) two values requires use of the diff_time() function.Ê

String, struct, and any pass by reference data types must be copied into the ProbeVue environment as they cannot be accessed directly from the watched process. If the memory location is paged out the copy will fail (silently) and the default behavior of ProbeVue is to NOT cause a page fault.

It is the authorÕs opinion that the List data type and related functions are worthless. Ð This statement really depends partially upon how List is actually implemented. If all data points are retained in a dynamic list then it is not worth using. If List only stores min, max, count, total, and a running average (derived from total / count) then the List and associated API offers some (code simplification) value Ð provided you never intend to reset the data on intervals (as there is no reset option for a List data type).